Origen

The bird's name and the verb swan, meaning ‘to go about in a casual or ostentatious way’, are the same word. The verb originated as military slang as recently as the 1940s, referring to the free movement of armoured vehicles. A swansong (early 19th century) or final public performance or work is based on German Schwanengesang, which refers to the classical legend that the normally mute swan is supposed to sing just before its death. The legend is also behind the long association of bards and poets with swans, hence Shakespeare's title the Swan of Avon.